A method for forming a shallow trench isolation structure. A substrate having a pad oxide layer and a first mask layer is provided. The first mask layer is patterned to form a first opening, a spacer is formed on the first mask layer sidewalls. The patterned first mask layer and the spacer are used as a hard mask, a portion of the pad oxide layer and the substrate are removed to form a shallow trench within the substrate. A liner layer is formed on the shallow trench surface. An insulation layer is deposited over the patterned first mask layer and within the shallow trench. Using the patterned first mask layer as a stop layer, a portion of the insulation layer above the patterned first mask layer surface is removed. Then, the patterned first mask layer and the spacer are removed. A patterned second mask layer having a second opening is formed on the substrate to expose the insulation layer and a portion of the pad oxide layer. The patterned second mask layer is used as a hard mask to remove the portion of the pad oxide layer, and then an oxide layer is formed by thermal oxidation process on the substrate. The second patterned mask layer and the pad oxide layer are removed, and then an isolation structure according to this invention is complete.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for forming a shallow trench isolation, comprising: providing a substrate; forming a first mask layer having a pattern exposing a portion of the substrate; forming a spacer on a sidewall of the first mask layer to reduce the exposed portion of the substrate; forming a shallow trench in the substrate with the first mask layer and the spacer as a mask; filling the shallow trench with an insulation layer; removing the first mask layer and the spacer; forming a second mask layer having the pattern of the first mask layer, so that the insulation layer and a portion of the substrate around the insulation layer are exposed; transforming the portion of the substrate around the insulation layer into an oxide layer; and removing the second mask layer.
2. The method of claim 1, further comprising a step of forming a pad oxide layer on the substrate before the step of forming the first mask layer.
3. The method of claim 2, wherein the spacer, the pad oxide layer and the substrate have different etching rates.
4. The method of claim 1, wherein the spacer includes silicon nitride.
5. The method of claim 1, further comprising a step of forming a liner layer on he shallow trench surface before the step of filling the shallow trench with the insulation layer.
6. The method of claim 2, further comprising a step of forming a liner layer on the shallow trench surface before the step of filling the shallow trench with the insulation layer, wherein the liner layer extends to a top corner of the shallow trench and connects with the pad oxide layer.
7. A method for forming a shallow trench isolation, the method comprising the steps of: providing a substrate; forming a first mask layer, wherein the first mask layer has a first opening to expose a part the substrate; forming a spacer on a sidewall of the first opening to narrow down the part of the substrate exposed by the first opening; removing the exposed portion of the substrate, so as to form a shallow trench; filling the shallow trench with an insulation layer; removing the first mask layer and the spacer; forming a second mask layer on the substrate with a second opening, wherein the second opening having a same dimension and a same position as the first opening; performing an oxidation process; and removing the second mask layer.
8. The method of claim 7, wherein the first mask layer includes a silicon nitride layer.
9. The method of claim 7, further comprising a step of forming a pad oxide layer on the substrate before the step of forming the first mask layer.
10. The method of claim 9, wherein the spacer, the pad oxide layer and the substrate have different etching rates.
11. The method of claim 7, wherein the spacer includes silicon nitride.
12. The method of claim 7, further comprising a step of forming a liner layer on the shallow trench surface before the step of filling the shallow trench with the insulation layer.
13. The method of claim 9, further comprising a step of forming a liner layer on the shallow trench surface before the step of filling the shallow trench with an insulation layer, wherein the liner layer extends to a top corner of the shallow trench and connects with the pad oxide layer.
14. The method of claim 7, wherein the step of forming the spacer further comprising: forming a dielectric layer on the substrate; and performing an etching back process to leave the spacer on the side wall of the first opening.
15. The method of claim 14, wherein the dielectric layer includes a silicon nitride layer.
16. The method of claim 7, wherein the insulation layer includes a silicon oxide layer.
17. The method of claim 7, wherein the step of removing the portion of the insulation layer includes using chemical mechanical polishing.
18. The method of claim 7, wherein the step of removing the first mask layer and the spacer includes using isotropic etching.
19. The method of claim 7, wherein the second mask layer includes a silicon oxide layer.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
December 18, 1999
November 27, 2001
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